Hi Van,
I had the same problem with Helene de Mer. There was no messenger line or holes for anything. What I did was to make holes in the the mast where required and then acquire some thin/long lead fishing sinkers and then put two or three of them on a fishing line and drop them through the holes where my cables would go. They then dropped through the mast to the bottom of the mast below the floor. The new cables have to come out there anyway and it does not matter so much if the holes are a little bigger at the bottom of the mast. There you can “fish” the sinkers out of the mast through the holes. Once you have the nylon line through, then you can change to some more substantial string. 2 or 3mm parachute cord is good, and then pull your cables through to the top.
It worked for me. I hope it works for you. Neel